The prior art devices used for making emergency repairs to holes in pressurized spacecrafts made by meteoroid impacts or other pressure wall breaches are designed for placement on the internal wall of the spacecraft through use of adhesives. These holes normally have rough, petalled, outer edges in that they result from meteors impacting the outer wall of the spacecraft and causing depressurization of the spacecraft. The prior art devices require a smooth, accessible, surface for placement of the device on the internal wall of the spacecraft, thus their use requires considerable cutting and grinding of the wall surface by pressure-suited astronauts prior to the placement of the device over the hole. The need for the cutting and grinding operations is a major drawback or disadvantage of such prior art devices. Another major drawback or disadvantage of such prior art devices results from the fact that many areas of a spacecraft are not readily accessible for repairing the hole, particularly those internal walls of the spacecraft behind and covered by equipment racks, utility lines and the like. An emergency repair to holes in these areas of the spacecraft would be very time consuming and burdensome in that it would often require a complete disassembly of the equipment racks and/or removal or rerouting of such utility lines and the like prior to the making of the repair by pressure suited astronauts.
The present invention overcomes the disadvantages or drawbacks of the prior art devices as well as provides several distinct advantages thereover in that it provides a pressure wall patch that is placed over and around the hole (damaged portion) from the exterior of the spacecraft. The device of the present invention requires no wall preparation (cutting, grinding etc.) prior to use, thus eliminating danger to pressure-suited astronauts from sharp hole edges and from tools used for cutting, grinding, etc. The device of the present invention can be used to repair a hole in the wall in an area of the spacecraft that is not readily accessible from the interior of the spacecraft without performing some major disassembly of the spacecraft. The device of the present invention, once in place, also allows safer, more permanent, wall repair to be conducted in a shirt sleeve environment from the interior of the spacecraft by the astronauts.
Typical spacecrafts, such as space vehicles or habitats, are comprised of a pressurized enclosure whose external surface, which may be flat, cylindrical or spherical, is generally formed of an isogrid (or orthogrid) structure. The isogrid structure is generally defined by upstanding ribs which isolate adjacent portions of the surface from each other and adds structural rigidity to the spacecraft.
The device of the present invention requires no redesign of the existing pressure walls of conventional spacecraft other than the possible prior addition of numerous, pre-drilled, shallow tapped holes in the intersecting or other areas of the existing isogrid structure or numerous holes pre-drilled in the existing isogrid structure generally parallel to the outer pressure wall surface.